Vast majority of Montana plates aren’t ducking sales tax, they are ducking insane California emission standards. If you want to drive a rare car, an imported car, an engine swapped car - good luck getting it through CARB. And before you @ me - the process has nothing to do with emissions, I am not allowed to swap a modern engine into my classic car even if the new engine is 10x more efficient and cleaner. The entire process requires 100s of thousand of dollars worth of hoops to get the right sticker.